One of the series that I'm looking forward to collecting is the Preacher series. I've heard it can be a bit... off-color, and therefore a bit interesting. As it is, I have not read a single issue that follows - this chronology is based solely on release date.
Preacher Special: Saint of Killers #1-4 Aug-Nov 1996
Preacher Special: The Story of You Know Who One-shot Dec 1996
Preacher Special: The Good Old Days One-shot Aug 1997
Preacher Special: Cassidy Blood and Whiskey One-shot Feb 1998
Preacher Special: One Man's War One-shot Mar 1998
Preacher Special: Tall in the Saddle One-shot Feb 2000